The present invention relates to a golf ball. More particularly, it relates to a multi-layer structure golf ball having a thread rubber layer, which has good shot feel (feeling at the time of hitting) and controllability as well as satisfactory flight performance and cut resistance.
Recently, ionomer resin has widely been used for cover material of golf balls (e.g. Japanese Patent Publication No. 49-27093 etc.). This is because the ionomer resin is superior in durability, cut resistance, rebound performance, etc. and it is easily processed.
However, since the ionomer resin has high hardness and rigidity, the resulting golf ball is poor in shot feel and controllability (ease of giving spin) in comparison with balata (transpolyisoprene) which has been used as cover material of a multi-layer structure golf ball containing a thread rubber layer.
In order to improve shot feel and controllability of the ionomer-covered golf balls, softening the ionomer resin has been intensively studied.
For example, Japanese Patent Laid-Open Publication Nos. 1-308577 and 5-3931 suggest to blend or mix a hard ionomer resin with a soft ionomer resin prepared by neutralizing a terpolymer of xcex1-olefin, an unsaturated carboxylic acid (e.g. acrylic acid, methacrylic acid, etc.) and an acrylate with sodium or zinc ion, thereby improving shot feel and controllability.
However, the blending of the soft ionomer resin as suggested by the above mentioned publications has not provided with the shot feel which is closed to the balata covered golf ball. Instead, the rebound performance and flight performance are adversely lowered by blending the soft ionomer resin and, therefore, sufficient technical effects have not been obtained.
Japanese Patent Laid-Open Publication No. 5-220240 suggests to improve shot feel and controllability by blending the ionomer resin with a polymer containing glycidyl groups. According to this method, shot feel and controllability are slightly improved but they are not sufficient and ionomer-covered gold balls having sufficient characteristics (particularly, rebound performance, flight performance, etc.) are still desired.
Under these circumstances, the present inventors have intensively studied cover properties to achieve excellent shot feel and controllability, which are close to those of the balata-covered golf balls, and excellent flight performance and cut resistance based on the ionomer resin.
A main object of the present invention is to provide a golf ball having good shot feel and controllability as well as satisfactory flight performance and cut resistance.
This object as well as other objects and advantages of the present invention will become apparent to those skilled in the art from the following description with reference to the accompanying drawings.